The American Community Survey (ACS) collects data throughout the year asking respondents to report their income for the 12 months preceding the interview month. Monthly Consumer Price Index (CPI) factors from the CPI-U-RS are used to inflation-adjust income to a reference calendar year (January through December).

Beginning in 2018, aggregate income deficit amounts presented in Detailed Tables B17008 and B17011 and mean income deficit amounts in Subject Tables S1701 and S1702 are similarly adjusted to reference year dollars. Before 2018, aggregate income deficit amounts and mean income deficit amounts were presented as reported and were not therefore in reference year dollars.